No abstract

The Grand Bend succession can be divided into three periods: a colonizing stage, up to 1600 years; a transition period from 1600 to 2900 years; and a persistent stage from 2900 to at least 4800 years. The colonizing stage is dominated by grasses, Juniperus spp. and Quercus prinoides. Transition begins when persistent species invade at certain points; the earliest species are usually Quercus velutina × rubra, Rhus aromatica, and Prunus virginiana. During the transitional period the patches of persistent vegetation grow until they coalesce. This marks the inception of the persistent stage during which the vegetation cover is predominantly oak–pine forest. Hence the path of succession does not differ from point to point but the rate of succession does. It is argued that the existence of distinct successional stages and the mode of transition between them support the organismal concept of vegetation.

Asymptotic increases in diversity, richness, and evenness are reported from a primary sand dune succession. Rapid increases in diversity and evenness were observed in the first 1000 years of the 4800 sampled; richness appears to increase little after 2000 years of succession.

Atlantic salmon Salmo salar L. farmed in south-east Tasmania, Australia, are susceptible to infection by the Tasmanian Rickettsia-like organism (TRLO), a Gram-negative bacterium. Here, we report the first isolation of TRLO from south-east Tasmania in pure culture and show that the bacterium is culturable on both specialised enriched agar and in cell culture using the CHSE-214 cell line. In vitro cultured TRLO was used to reproducibly elicit disease in Atlantic salmon parr held in fresh water. In inoculated fish, TRLO was observed intracytoplasmically in peripheral blood leucocytes, suggesting that these cells are responsible for haematogenous dispersal of the bacterium within the host. Fish with experimentally induced disease presented with gross and histopathological changes similar to TRLO-infected fish at commercial marine farms. TRLO was also isolated in culture from farmed Atlantic salmon in the Tamar River and Macquarie Harbour production areas in Tasmania, both of which have no history of TRLO-associated disease. These TRLO isolates appear to be serologically distinct from each other as well as from isolates obtained from south-east Tasmania, linking each serotype to a specific geographical location within Tasmania. Despite the lack of clinical evidence of TRLO-linked disease in fish grown in the Tamar River and Macquarie Harbour, experimental infection trials demonstrably showed the pathogenic potential of these TRLO serovars. Together, these data provide evidence that TRLO is a fastidious, facultative intracellular bacterium and confirm TRLO as a pathogen of Atlantic salmon, causing a disease designated Tasmanian salmonid rickettsiosis.KEY WORDS: Rickettsia-like organism · TRLO · Atlantic salmon · Salmo salar · Culture · Pathogenicity · Tasmania Resale or republication not permitted without written consent of the publisherDis Aquat Org 122: [85][86][87][88][89][90][91][92][93][94][95][96][97][98][99][100][101][102][103] 2016 RLO (Khoo et al. 1995, Athanassopoulou et al. 2004, Corbeil et al. 2005, Wu et al. 2005 or P. salmonis-like organism (Antonio et al. 2000, Chen et al. 2000a,b, Mauel et al. 2003 until their taxonomic status can be formally resolved. This includes the Tasmanian RLO (TRLO), a bacte rium detected in Atlantic salmon Salmo salar L. farmed on the south-east coast of Tasmania, Austra lia (Corbeil et al. 2005).TRLO is an intracellular, Gram-negative coccoid bacterium that emerged in the summer of 2001 (Department of Primary Industries, Parks, Water and Environment [DPIPWE] unpublished data). Since then, TRLO has been implicated in minor sporadic outbreaks of disease which have typically coincided with the annual peak in water temperature. The disease is characterised by a high morbidity rate which results in significant production loss through reduced feed intake but relatively low mortality, less than 10% of affected stock. During outbreaks, affected fish are commonly co-infected with the Tasmanian Atlantic salmon reovirus (TSRV; Zainathan et al. 2015), and it is not known wh...

A method of classifying phytosociological data into non exclusive groups is described. It is an agglomerative, polythetic technique consisting of two stages: in the first stage, groups are formed and in the second, the groups are classified hierarchically. Both normal and inverse analyses of a set of data from limestone grikes in Bruce County, Ontario, are presented as an example of the application of the method, which, it is suggested, is effective in handling species of wide ecological amplitude and samples containing more than one element of vegetational mosaics. The application of Fourier analysis to the problem of determining the optimum number of groups in a classification is advocated.